Barley resistance

Despite vast efforts over 20 years, rice remains one of the most salt-sensitive of crops. Efforts have centred on screening the existing germplasm, and the more resistant varieties have proved to be older, traditional (and therefore non-dwarfed) land races. Although some of their resistance has been incorporated into modern varieties, these have not increased in resistance beyond that of their parents, and do not achieve the resistance of barley or wheat (Ponnamperuma, 1984). 

Hanson, A.D., Nelson, C.E., Pedersen, A.R. Everson, E.M. (1979). Capacity for proline accumulation during water stress in barley and its implications for breeding for drought resistance. Crop Science, 19, 489-93. 

There is very little information on cultivar differences with respect to (i) resistance to infection by P. verrucosum and (ii) OTA formation (Hokby et al., 1979 Axberg el al., 1997). The latter performed a laboratory experiment with six artificially inoculated cultivars of barley and three of wheat. After incubation for 23 weeks at approximately 19% moisture, the barley cultivars contained between 6 and 350 and the wheat cultivars between 25 and 890 ng OTA g 1 grain. In another study, Elmholt and Rasmussen (2005) reported that two of four cultivars of spring spelt from the same field contained 18 and 92 ng OTA g 1, respectively, while the other two contained less than 0.5 ng OTA g As differences in OTA neither correlated with moisture content at harvest nor with the level of P. verrucosum, they were probably caused by differences in cultivar sensitivity. This should, however, be further studied. 

Buerstmayr H, Legzdina L, Steiner B and Lemmens M (2004), Variation for resistance to Fusarium head blight in spring barley , Euphytica, 137, 279-290. 

Islam, A.K.M.R. and S.B. Powles. 1988. Inheritance of resistance to paraquat in barley grass Hordeum glaucum Steud. Weed Res. 28 393-397. 

Kristensen BK, Bloch H, Rasmussen SK (1999) Barley coleoptile peroxidases. Purification, molecular cloning, and induction by pathogens. Plant Physiol 120 501-512 Kubanek J, Jensen PR, Keifer PA, Sullards MC, Collins DO, Fenical W (2003) Seaweed resistance to microbial attack a targeted chemical defense against marine fungi. Proc Natl Acad Sci USA 100 6916-6921... 

In this paper we summarize our work on the role of indole alkaloids and hydroxamic acids on the resistance of cereals to aphids. In addition, we describe the effects of water stress on susceptibility of barley to aphids. 

When injected into primary leaves of different cereals, the stem rust elicitor causes symptoms which closely resemble the respective resistance reactions of these species against the attack by stem rust of wheat, i.e., lignification in barley and rye, brown spots in oat, and no visible symptoms in maize (66). 

Two mutant lines of yellow mosaic virus resistant barley were found in ca. 50,000 M2 families. The character of the resistance in a field was not changed over three generations [114]. 

Studies to determine the level of resistance or susceptibility due to foliage quality and tree physical parameters of Douglas-flr to the budworm were conducted at the Boulder, Montana and Barley Canyon, New Mexico sites. The study at the Montana site Involved trees exposed to moderate budworm densities, while the study at Barley Canyon was done using budworm that were placed on trees that had very low natural densities of budworm. 

Resistance to insects has been successfully selected and introduced into important cultivars of a number of plant species including potatoes, wheat, corn, grapes, alfalfa, barley, beans sorghum, rice and sugar cane (25). This resistance is usually due to a combination of factors and only in a few cases is a single chemical factor identifiable as responsible for resistance (32). 

The ubiquitous plant compound chlorogenic acid (isolated from green coffee beans) is formed by transesterification with the glycoside cinnamoyl-glucose.187 Coumaroyl-CoA is converted into monomeric and dimeric amides with agmatine, which provides barley plants with resistance to mildew.188 Similar compounds with various polyamines and derived from p-coumaric, caffeic, ferulic, or sinapic acid appear to... 

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